Small electric devices and communication devices, such as a digital audio player and a mobile phone, which can be placed in clothing or in a bag and carried, are often subject to impact on their surfaces when they are accidentally dropped or hit with other articles in the bag.
To address the problem, the housing case of such a device needs to have a highly robust hard coat layer coated on the front portion of the housing case; in particular, the portion that covers an LCD or any other display screen, in order to enhance scratch resistance. For example, Patent Document 1 discloses a housing case 100 (see FIG. 38) manufactured from a continuous film having a peelable layer, a hard coat layer 103, a printed layer, and an adhesive layer successively stacked on a base film. The hard coat layer 103 comprises layered hard coats for hardening the front portion of the housing case 100, and the printed layer includes a plurality of printed patterns, each of which having a non-printed portion 102. The housing case 100 is manufactured by continuously passing the continuous film through a glass insert molding die, injecting a transparent synthetic resin onto the adhesive layer of the continuous film in the glass insert molding die, and drawing the continuous film into the shape of the cavity of the glass insert molding die so as to form a synthetic resin layer 101. After the synthetic resin layer has hardened, the hard coat layer 103, the printed layer, the adhesive layer, and the synthetic resin layer 101 are removed from the base film and the peelable layer. In FIG. 38, reference numeral 104 denotes a display window that covers an LCD display screen, and reference numeral 105 denotes a button hole.
The hard coat layer 103 is typically manufactured by forming a thin coated film, ranging from approximately 3 to 10 μm in thickness, made of a thermoset resin, a UV curable resin, or any other suitable active energy radiation polymerizable resin on a plastic substrate directly or with an interposed primer layer having a thickness ranging from 0.03 to 0.5 μm.
The hard coat layer 103 comprising a thin coated film, however, is not hard enough as the front portion of the housing case; in particular, the portion that covers an LCD or any other display screen where high hardness is required.
The invention has therefore been contrived in view of the above problem. An object of the invention is to provide a housing case, the front portion of the housing case; in particular, the portion of the housing case that covers an LCD or any other display screen, being adequately hardened. Other objects of the invention are to provide a method for manufacturing the housing case and a glass insert molding die used in the same.
[Patent Document l] Japanese Laid-open Patent Application No. 2001-36258